ISO 17491的本部分规定了在最低试验设置（方法1）或 更严格的测试设置（方法2），用于评估气密服对气体向外泄漏的阻力 例如，通过必要的开口、紧固件、接缝、物品之间的接口区域、气孔和任何 建筑材料的缺陷。 本试验不模拟气体向内渗透。虽然对佩戴者的危险 由于向内泄漏，本试验方法评估气密后空气向外泄漏 西装已经充气，以拉伸建筑材料，从而使测试方法能够检测 非常小的缺陷，如孔洞、裂缝或撕裂。

This part of ISO 17491 specifies a method to be performed either at minimum test settings (Method 1) or at more rigorous test settings (Method 2), for assessing the resistance of a gas-tight suit to outward leakage of air through, for example, essential openings, fastenings, seams, interface areas between items, pores and any imperfections in the construction materials. This test does not simulate penetration by gases in an inward direction. Although the danger to the wearer arises from leakage in an inward direction, this test method assesses the outward leakage of air after the gastight suit has been inflated so as to stretch the construction material, thereby enabling the test method to detect very small imperfections, such as holes, splits or tears.